The present disclosure relates to a pipe connection tolerating or having an axial and radial play as well as an angle compensation. The pipe connection more particularly relates to a pipe connection in exhaust pipes of internal-combustion engines. The pipe connection includes an interior part which is constructed at the end of one pipe and which is enveloped by a bell part at the end of another pipe. At least one lamellar ring is held in an annular groove in the radially outer surface of the interior part or in the radially inner surface of the bell part. The at least one lamellar ring is tensioned against the radially inner surface of the bell part or against the radially outer surface of the interior part. The radially inner surface of the bell part and/or the radially outer surface of the interior part are constructed as a spherical segment surface, which is concave with respect to the lamellar ring, or as a concavely spherical surface. The at least one lamellar ring is tensioned against the spherical segment surface or the spherical surface.
A sealing of the pipe connection with no leakage or an extremely low leakage of environmentally hazardous mediums, such as exhaust gases of internal-combustion engines, is becoming increasingly important against the background of a raised environmental awareness and legal regulations, such as the Air Ordinance TA 2003 or the VDI Standard 2440.
The at least one lamellar ring is directed to sealing off the pipe connection as hermetically as possible with respect to the environment. Such lamellar rings include a thin steel band or are made of another material, are constructed simply and require a small installation space in the axial as well as in the radial direction. They can, therefore, easily be retrofitted into existing pipe connections. In addition, because of their conventional metal construction, they are heat-resistant and break-proof and are therefore excellently suitable for sealing a pipe connection with respect to aggressive and high-temperature mediums. As a result, they are advantageous as sealing devices in exhaust pipe connections, particularly with respect to hot engine exhaust gases of temperatures of up to 730° C.
The effect of such a lamellar ring is based on the same effect as occurs in the case of diaphragm seals. That is, it deflects the flow away from the working diameter toward the groove base and, because of the very small still exposed gap, forms a throttle there, at which pressure energy is lost. As a result of the flow deflection and the throttling, the lamellar ring reduces a high pressure level to a low level and reduces a flow past the working diameter.
A pipe connection is known from German Patent Document DE 41 36 799 C2, where the radially inner circumferential surface of the bell part, as well as the radially outer circumferential surface of the interior part, are cylindrical and several lamellar rings are held in outer grooves of the interior part. A small clear gap exists between the groove base of the outer grooves and the radially inner circumferential surface of the lamellar rings. On the other hand, as a result of the prestressing caused by their outside diameters, which are greater than the radially inner circumferential surface of the bell part, the lamellar rings rest sealingly against the bell part by their radially outer circumferential surface. This permits a certain axial and radial play as well as an angle compensation between the two pipes.
Especially because of the fact that nowadays a large number of assemblies are crammed into the engine compartment and the engine movements of self-ignition internal-combustion engines are often large, it is necessary that pipe connections in exhaust pipes of internal-combustion engines have constructions that are as flexible as possible. This requirement with respect to pipe connections exists also in other fields of technology.
From German Patent Document DE 32 41 750 A1, a pipe connection is known which, with the exception of a radial gap, corresponds to the pipe connection of the initially mentioned type. In such a case, the radially inner surface of the bell part and the radially exterior surface of the interior part are constructed as spherical segment surfaces concave with respect to the lamella ring. In this case, the at least one lamellar ring is accommodated in an annular groove of the interior part and is tensioned against the spherical segment surface of the bell part. However, no radial compensation is provided between the interior part constructed as a sliding ring and the exterior part constructed as a slide bush. Thus, during the mounting, the sliding ring bush has to be forced open by a suitable tool in order to then slide the two bush halves axially over the sliding ring and then join them again.
The present disclosure relates to a pipe connection configured such that it can be mounted easily and includes desirable tightness properties.
The present disclosure is related to a pipe connection for exhaust pipes of internal-combustion engines. The pipe connection includes an axial and radial plug and an angle compensation. The pipe connection further includes a first pipe, a second pipe and an interior part at an end of the first pipe. The interior part is enveloped by a bell part at an end of the second pipe. The pipe connection further includes at least one lamellar ring held in an annular groove in either a) a radially outer surface of the interior part or b) a radially inner surface of the bell part. The at least one lameller ring is tensioned against either a) the radially outer surface of the interior part or b) the radially inner surface of the bell part. One of a) the radially outer surface of the interior part and b) the radially inner surface of the bell part are constructed as a concave surface. The at least one lameller ring is tensioned against the concave surface. Further included is at least one tensioning ring that is supported on a groove base and is held in the annular groove. The at least one tensioning ring generates an elastic prestressing of the at least one lameller ring against either a) the radially outer surface of the interior part or b) the radially inner surface of the bell part.
Regarding the pipe connection, according to the present disclosure as noted above, the radially inner surface of the bell part and/or the radially outer surface of the interior part is/are constructed as a spherical segment surface concave with respect to the lamellar ring, or as a concavely spherical surface. The at least one lamellar ring is tensioned against the spherical segment surface or the spherical surface, which then forms the so-called working diameter of the lamellar ring. In this case, the prestressing of the at least one lamellar ring provides a gap-free sealing with respect to the working diameter, while a small gap is left free toward the groove base of the annular groove. As a result, a ball-and-socket joint is essentially implemented at the pipe ends and is sealed by lamellar rings. In such a case, the lamellar rings now essentially follow a circular path when one pipe is moved relative to the other pipe in an angular manner.
Depending on the radius of the pipes and of the spherical segment surfaces, a significantly greater angle compensation can thereby be implemented. An axial and radial play or compensation can also take place between both pipes. That is because during a relative movement of the two pipes in the axial or radial direction, the at least one lamellar ring can deflect toward the groove base when the working diameter situated opposite the annular groove is reduced because of the relative movement.
According to the present disclosure, a tensioning ring supported at the groove base is held in the annular groove, which tensioning ring generates an elastic prestressing of the at least one lamellar ring against the radially inner surface of the bell part or against the radially outer surface of the interior part.
On the one hand, the sealing effect is thereby increased. On the other hand, the elastic prestressing centers the bell part with respect to the interior part. This is desired particularly in the case of vibration-stressed pipe connections, such as exhaust gas systems of motor vehicle internal-combustion engines. The reason is that there is a risk that the connection between the bell part and the interior part, which has radial play because of the required compensating movements, is excited to carry out vibrations such that the bell part impacts on the interior part and thereby causes undesirable noise and damage.
In contrast, the prestressing exercised by the tensioning ring provides that, although during the mounting of the pipe connection radial compensation can take place as a result of elastic deformations of the tensioning ring, under the effect of a dynamic load, with a corresponding design of the tensioning ring, a direct contact is avoided between the bell part and the interior part.
In view of an operating temperature range of, for example, minus 30° C. outside temperature up to approximately 700° C. of the exhaust gas guided through the pipe connection, the prestressing generated by the tensioning ring also provides a compensation of heat-caused deformations of the pipe connection parts, particularly of the lamellar rings.
In an embodiment of the present disclosure, the at least one lamellar ring is held in an outer groove of the interior part and is tensioned against the radial inner circumferential surface of the bell part. The radially inner surface of the bell part and the radially outer surface of the interior part are constructed as concave spherical-segment surfaces with the same curvature direction. A good guidance or contact of the interior part onto the exterior part is obtained if the radii of the spherical segment surfaces or of the spherical surfaces are essentially identical.
Several lamellar rings may be arranged axially behind one another in the annular groove, which has a favorable effect with a view to a multiple deflection of the flow of the pressure medium. When several lamellar rings are arranged in the annular groove, those of the same type are used. Because of the construction as a spherical-segment surface or as a spherical surface, the lamellar rings will then each have different outside diameters when they rest on the working diameter, which equals a wide elastic sealing. The more such lamellar rings are held in an annular groove, the better the close contact on the working diameter.
In such a case, for example, one or more single-wound lamellar rings can be used which have an axial abutting opening and are made of a steel band extending in a plane. Such single-wound lamellar rings can be produced cost-effectively, and their prestressing against the groove base or against the working diameter is easily preadjustable.
In accordance with to another embodiment of the present disclosure, double-wound lamellar rings are used. In the relaxed condition of the double-wound lamellar ring, the ends of the double windings project toward the inside or outside deviating from a circular shape formed by the remainder of the double-wound lamellar ring. In addition, in the tensioned condition of the double-wound lamellar ring, the ends of the double windings are aligned with this circular shape. The ends, which project to the inside or outside with respect to the circular shape, will then have the effect that the double windings are pressed toward the outside or toward the inside in the installed condition. The roundness of the closed double winding over 360 degrees ensures a firm contact with the groove base of the annular groove or with the working diameter.
An interior part and/or the bell part can be produced as separate components and can be fastened to the ends of one pipe and/or of the other pipe by, for example, welding.
Other aspects of the present disclosure will become apparent from the following descriptions when considered in conjunction with the accompanying drawings.